She and other parents questioned the strong-arm tactics of Local 1181 of the Amalgamated Transit Union — whose members have been found to be intimidating and blocking yellow-bus drivers who don’t belong to the union from running their routes.

One union loyalist was arrested after he dangerously lay down in front of a bus departing a Bronx depot Thursday, and the Department of Education has found similar union interference at 10 other depots since the strike’s launch a day earlier.

“That behavior is just making it worse,’’ Grandison said.

Maria Arias, 33, another mom with a sixth-grader at Evergreen, added, “There are a lot of disabled kids having a lot of issues getting to school.”

Local 1181 says it was driven to strike by the city‘s elimination of long-held work protections that ensured that senior members wouldn’t lose their jobs when busing contracts changed hands between companies.

City officials say the busing contracts hadn’t been competitively bid out since 1979 — which they point to as a large part of the reason for the city’s annual yellow-busing tab of more than $1 billion.

They add that the union is asking for protections that its members don’t currently have in any nearby school district — including those in Long Island and Connecticut.

The work stoppage kept nearly 70 percent of the 7,700 school-bus routes from operating yesterday, about the same as Thursday.